The field of the disclosure relates generally to heat transfer devices and, more specifically, to closed loop heat transfer devices and variable area heat transfer devices.
Some existing aircraft include multiple turbofan engines, each coupled to a starter/generator. The starter/generator is used both to start the turbofan engine and extract electrical power from the turbofan engine once the turbofan engine is started. The extracted electrical power is then routed to electrical systems on the aircraft.
Existing starter/generators create heat that must be dissipated to prevent overheating and subsequent system failure. Some aircraft utilize an air-cooled oil cooler (i.e., a heat exchanger) designed for this purpose. The heat exchanger receives hot cooling oil from the starter/generator via a hot oil supply, and returns cooled oil to the starter/generator via a cool oil return. Within the heat exchanger, cold air cools the initially hot oil. The cold air can be received from a cold air supply, which is coupled to an air source, for example, an air scoop located behind the fan of the turbofan engine. A warm air return returns air warmed by the oil, for example, by reintroducing the air to the fan flow, or by dumping the air overboard the aircraft. Other aircraft transfer heat from hot cooling oil to another, cooler fluid such as, for example, a cooling fluid or engine fuel. Some of these known systems are relatively large and/or heavy and may increase the weight of the aircraft in which they are used.